We show that the mode-locking region of the family of quasi-periodically forced Arnold circle maps with a topologically generic forcing function is dense. This gives a rigorous verification of certain numerical observations in [M. Ding, C. Grebogi and E. Ott. Evolution of attractors in quasiperiodically forced systems: from quasiperiodic to strange nonchaotic to chaotic. Phys. Rev. A 39(5) (1989), 2593–2598] for such forcing functions. More generally, under some general conditions on the base map, we show the density of the mode-locking property among dynamically forced maps (defined in [Z. Zhang. On topological genericity of the mode-locking phenomenon. Math. Ann. 376 (2020), 707–72]) equipped with a topology that is much stronger than the $C^0$ topology, compatible with smooth fiber maps. For quasi-periodic base maps, our result generalizes the main results in [A. Avila, J. Bochi and D. Damanik. Cantor spectrum for Schrödinger operators with potentials arising from generalized skew-shifts. Duke Math. J. 146 (2009), 253–280], [J. Wang, Q. Zhou and T. Jäger. Genericity of mode-locking for quasiperiodically forced circle maps. Adv. Math. 348 (2019), 353–377] and Zhang (2020).

Competition policy is one important aspect of trade liberalization. However, when examining preferential trade agreements (PTAs), a major type of policy tools to liberalize trade, competition provisions are revealed not to be uniformly distributed across these treaties. What explains the variation in the design of competition clauses in PTAs? Borrowing insights from the rational design of international institutions and combining them with those from treaty ratification and policy diffusion literatures, I identify five major causal mechanisms through which competition provisions are incorporated into PTAs. In evaluating them, I employ a range of operationalization techniques to capture the proposed mechanisms. A treaty-level analysis of 319 PTAs over the period 1960–2015 lends strong and robust support to most of the hypothesized relationships. By integrating theoretical frameworks across international political economy literatures with that from law and economics scholarship, this study demonstrates the utility of political science thinking to the real-world international law-making.

Ketosis is a metabolic disease of dairy cows often characterized by high concentrations of ketone bodies and fatty acids, but low milk protein and milk production. The Janus kinase 2 (JAK2)-signal transducer and activator of transcription 5 (STAT5) and the mechanistic target of rapamycin (mTOR) signaling pathways are central for the regulation of milk protein synthesis. The effect of high levels of fatty acids on these pathways and β-casein synthesis are unknown in dairy cows with clinical ketosis. Mammary gland tissue and blood samples were collected from healthy (n = 15) and clinically-ketotic (n = 15) cows. In addition, bovine mammary epithelial cells (BMEC) were treated with fatty acids, methionine (Met) or prolactin (PRL), respectively. In vivo, the serum concentration of fatty acids was greater (P > 0.05) and the percentage of milk protein (P > 0.05) was lower in cows with clinical ketosis. The JAK2-STAT5 and mTOR signaling pathways were inhibited and the abundance of β-casein was lower in mammary tissue of cows with clinical ketosis (P > 0.05). In vitro, high levels of fatty acids inhibited the JAK2-STAT5 and mTOR signaling pathways (P > 0.05) and further decreased the β-casein synthesis (P > 0.05) in BMEC. Methionine or PRL treatment, as positive regulators, activated the JAK2-STAT5 and mTOR signaling pathways to increase the β-casein synthesis. Importantly, the high concentration of fatty acids attenuated the positive effect of Met or PRL on mTOR, JAK2-STAT5 pathways and the abundance of β-casein (P > 0.05). Overall, these data indicate that the high concentrations of fatty acids that reach the mammary cells during clinical ketosis inhibit mTOR and JAK2-STAT5 signaling pathways, and further suppress β-casein synthesis.

The North Qilian Orogenic Belt is on the northeastern margin of the Tibetan Plateau. It is connected with the Alxa Block in the north and the Tethyan orogenic assemblage in the south. The Lower Silurian Angzanggou Formation, deposited in the northern area of the North Qilian Orogenic Belt, is the most important for revealing the architecture and orogenic processes of the North Qilian Belt. Provenance analysis of the Angzanggou Formation can reveal not only the tectonic evolution of the central orogenic belt of China but also Palaeozoic Asia plate reconstructions. Petrographic analysis indicated that the compositional and textural maturity of the sandstones was low. The detrital composition of the Angzanggou Formation samples consists of quartz (8–14 %), feldspar (6–29 %) and lithic fragments (56–86 %). The sandstones could be classified as litharenites or feldspathic litharenites. The detrital modal composition suggests that these sandstones were probably deposited in a fore-arc basin. The element ratios and some discrimination diagrams based on geochemistry indicate that felsic and intermediate rocks were the main source rocks. The SiO2/Al2O3 ratio, the index of chemical variability and the Th/Sc versus Zr/Sc discrimination diagram suggest that the compositional maturity and degree of recycling were moderate to low. The index of alteration (CIA) and the A–CN–K diagram indicate the intensity of weathering was moderate. The discrimination diagrams based on major and trace elements and petrographic discrimination diagrams imply that the Angzanggou Formation rocks were derived from a continental island arc, and a sedimentary cover probably overlaid the volcanic arc. Therefore, we infer that during Early Silurian time the North Qilian Belt sediments accumulated in a fore-arc basin.

Conventional methods for determination of trace drug residues are either time consuming or labor intensive or require large specialized instruments, which hamper their practical applications in field analysis. Here, we present a rapid and quantitative surface-enhanced Raman scattering (SERS) detection method coupled with a portable Raman spectrometer for determination of trace drug residues on fish surface. Graphene oxide (GO) decorated popcorn-like Ag nanoparticles (NPs) on Cu plate (GO/AgNPs/Cu) were fabricated by a facile approach and directly employed as a robust SERS detection substrate. For practical SERS detections, trace-level residues of crystal violet (10−8 M, 4.1 ng/g) and malachite green (10−8 M, 3.6 ng/g) could be readily detected by simply swabbing the contaminated fish scale surface with the SERS substrate. Importantly, SERS detection was quantitatively realized in the broad linear concentrations. Compared with lab-based Raman spectrometer with large footprints, our method has potential applications in practical rapid, accurate, and on-site SERS determination.

At room temperature (RT), Fe2Mo3O12 is stable in monoclinic structure phase and above 780 K it transforms to an orthorhombic phase. Experiment shows that in the high temperature orthorhombic phase, the material exhibits low or negative thermal expansion property. In the paper, new compounds with the formula Fe2–x(ZrMg)0.5xMo3O12 (x = 0–1.8) are reported. The compounds are designed and synthesized to reduce the phase transition temperature of the Fe2Mo3O12 by substitutional co-incorporation of Zr4+ and Mg2+ in it. It is found that the monoclinic-to-orthorhombic phase transition temperature can be lowered effectively by the co-incorporation. The orthorhombic phase of Fe0.4(ZrMg)0.8Mo3O12 may be obtained at RT and it may keep the orthorhombic structure as low as 103 K. Meanwhile, the co-incorporation of Zr4+ and Mg2+ may tailor the coefficient of thermal expansion (CTE) of the Fe2Mo3O12 and the near-zero CTEs are obtained for the compound around x = 1.7 (Fe0.3(ZrMg)0.85Mo3O12). This work paves the way toward developing low-cost and near-zero thermal expansion materials over wide temperature ranges.

The morphology of early hydrates of a cement clinker was studied by SEM and EDS. The hydrates were formed on thin plates cut from the clinker and immersed in a solution containing Ca(OH)2, CaSO4·2H20, and varying amounts of sucrose and KOH. The results show the different influences of sucrose and of KOH on the formation of the hydrates, in particular on the crystallization of AFt. The sucrose plays a leading role, and altered the time of primary formation of AFt and its morphology. KOH did not. In CaSO4·2H20 saturated solution without sucrose, regardless of the presence or absence of Ca(OH)2, the foil -like hydrates, CxAHy are formed as the first result of reaction of C3A with water. Then CxAHy reacts with CaSO4·2H20 to form AFt. However, in the presence of sucrose the C3A reacts directly with CaSO4·2H20 to form AFt. It is supposed that sucrose acts as a catalyst for the formation of AFt crystals. During the early stage of cement hydration, AFt crystals appear to form by both topochemical and by through-solution reaction mechanisms.